The Collaborative International Dictionary of English v.0.48:

Vertical \Ver"ti*cal\, a. [Cf. F. vertical. See Vertex.]
   [1913 Webster]
   1. Of or pertaining to the vertex; situated at the vertex, or
      highest point; directly overhead, or in the zenith;
      perpendicularly above one.
      [1913 Webster]

            Charity . . . is the vertical top of all religion.
                                                  --Jer. Taylor.
      [1913 Webster]

   2. Perpendicular to the plane of the horizon; upright; plumb;
      as, a vertical line.
      [1913 Webster]

   Vertical angle (Astron. & Geod.), an angle measured on a
      vertical circle, called an angle of elevation, or
      altitude, when reckoned from the horizon upward, and of
      depression when downward below the horizon.

   Vertical anthers (Bot.), such anthers as stand erect at the
      top of the filaments.

   Vertical circle (Astron.), an azimuth circle. See under
      Azimuth.

   Vertical drill, an upright drill. See under Upright.

   Vertical fire (Mil.), the fire, as of mortars, at high
      angles of elevation.

   Vertical leaves (Bot.), leaves which present their edges to
      the earth and the sky, and their faces to the horizon, as
      in the Australian species of Eucalyptus.

   Vertical limb, a graduated arc attached to an instrument,
      as a theodolite, for measuring vertical angles.

   Vertical line.
      (a) (Dialing) A line perpendicular to the horizon.
      (b) (Conic Sections) A right line drawn on the vertical
          plane, and passing through the vertex of the cone.
      (c) (Surv.) The direction of a plumb line; a line normal
          to the surface of still water.
      (d) (Geom., Drawing, etc.) A line parallel to the sides of
          a page or sheet, in distinction from a horizontal line
          parallel to the top or bottom.

   Vertical plane.
      (a) (Conic Sections) A plane passing through the vertex of
          a cone, and through its axis.
      (b) (Projections) Any plane which passes through a
          vertical line.
      (c) (Persp.) The plane passing through the point of sight,
          and perpendicular to the ground plane, and also to the
          picture.

   Vertical sash, a sash sliding up and down. Cf. French
      sash, under 3d Sash.

   Vertical steam engine, a steam engine having the crank
      shaft vertically above or below a vertical cylinder.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Vertical \Ver"ti*cal\, n.
   1. Vertical position; zenith. [R.]
      [1913 Webster]

   2. (Math.) A vertical line, plane, or circle.
      [1913 Webster]

   Prime vertical, Prime vertical dial. See under Prime,
      a.
      [1913 Webster]

WordNet (r) 3.0 (2006):

vertical
    adj 1: at right angles to the plane of the horizon or a base
           line; "a vertical camera angle"; "the monument consists
           of two vertical pillars supporting a horizontal slab";
           "measure the perpendicular height" [syn: vertical,
           perpendicular] [ant: horizontal, inclined]
    2: relating to or involving all stages of a business from
       production to distribution
    3: upright in position or posture; "an erect stature"; "erect
       flower stalks"; "for a dog, an erect tail indicates
       aggression"; "a column still vertical amid the ruins"; "he
       sat bolt upright" [syn: erect, vertical, upright] [ant:
       unerect]
    4: of or relating to different levels in a hierarchy (as levels
       of social class or income group); "vertical social mobility"
    n 1: something that is oriented vertically
    2: a vertical structural member as a post or stake; "the ball
       sailed between the uprights" [syn: upright, vertical]

Moby Thesaurus II by Grady Ward, 1.0:

88 Moby Thesaurus words for "vertical":
   abrupt, acmatic, apical, arrowlike, azimuth circle, bluff, bold,
   bolt upright, breakneck, capital, chief, consummate, dead straight,
   direct, downright, erect, even, flat, head, headlong, headmost,
   highest, horizontal, in a line, level, lineal, linear, maximal,
   maximum, meridian, meridional, normal, orthodiagonal, overmost,
   paramount, perpendicular, plumb, plunging, precipitous, preeminent,
   rampant, rapid, rearing, rectilineal, rectilinear, right,
   right angle, ruler-straight, sharp, sheer, smooth, stand-up,
   standing up, steep, straight, straight-cut, straight-front,
   straight-side, straight-up, streamlined, summital, supreme,
   tip-top, top, topmost, true, ultimate, unbending, unbent, unbowed,
   unbroken, uncurved, undeflected, undeviating, undistorted,
   uninterrupted, unswerving, unturned, up-and-down, upended, upmost,
   uppermost, upraised, upreared, upright, upstanding,
   vertical circle, zenithal